ACE Weekly 08/23/2011 - 08/29/2011 All ACE spacecraft subsystems are performing nominally. ======================================================================== Orbit/Attitude: No maneuvers were completed this week. The next attitude maneuver is scheduled for Tuesday 08/30/2011. ======================================================================= OCRs: DOY 238 (08/26/2011) 1520-1527z SWICS Three emergency commands from the SWICS safing procedure were executed to reduce the voltages on the instrument. A large background had started around Tuesday 08/23/2011 (DOY 235) and the commands were sent to prevent possible damage to the instrument. The instrument team is analyzing their data to decide further action. (AR#S11-0002). ======================================================================== Activities: Data Capture: 99.98% DOY 233-240 2011 There were 146 seconds of data missing on DOY 238 2011 from 0518-0526z. This was due to a combination of factors including SSRA being stuck in playback, the SSR restarting playback while DSN was first acquiring the high data-rate and no SSR redumps performed when we're behind in the SSR playback. 2 05:18:02-05:18:03 4 05:25:17-05:25:20 59 05:23:25-05:24:23 7 05:25:23-05:25:29 8 05:24:26-05:24:33 3 05:25:32-05:25:34 4 05:24:35-05:24:38 36 05:25:44-05:26:19 23 05:24:50-05:25:12 DSS-54 has had problems for the past week. ACE released time to help other missions impacted by the DSS-54 outage. Monday 08/22/2011 (DOY 234) pass shortened 1 hour for SOHO Friday 08/26/2011 (DOY 238) pass shortened 2 hours 5 minutes for WIND The GRAIL mission is expected to launch 09/08/2011. ACE has reduced DSN antenna time during September. The current schedule has ACE losing ~15% data over 3 weeks in September. The data loss will be greater if there are problems with any of the passes. NOAA Space Weather Prediction Center (SWPC) uses 3 main sites to track ACE in-between DSN passes: NICT/Japan, DLR/Germany and WCDA/Wallops,Virginia. WCDA (Wallops) shut down over the weekend due to Hurricane Irene. NOAA acquired AFSCN time on Sunday 08/28/2011 from 13:50-17:15z and 2045-2145z. This was the first operational use of the new VAFB SCD and network route via the MMOC. The data flow was successful after NOAA SWPC performed some investigation. NOAA's processing of SWEPAM data stopped during this time, but was restored at 1600z Monday 08/29/2011. ======================================================================== Anomalies: DOY 238 08/26/2011 S-ACE-0542 S10-0008 SSR A Stuck in Playback When the SSR playback is longer than the pass, the SSR is commanded to idle before switching to the low-rate (RTSW) data format. The pass was shortened for WIND and the SSR was not commanded to idle before the new EOT. Impact: The ground procedures are designed to handle this contingency. However, 146 seconds of data was lost because redumps were not performed. This has occurred 6 other times in the past. DOY 238 08/26/2011 S-ACE-0543 S11-0002 SWICS problems The instrument team found an abnormally large and possibly growing background starting around Tuesday 08/23/2011 (DOY 235). The trigger rate on SWICS started increasing to 10 times normal. There was concern that the instrument might be degraded, so the instrument was commanded to lower the MCP detector high voltage and the post-acceleration voltage on Friday 08/26/2011 (DOY 238). Impact: The instrument team is analyzing their data to decide further action.